The present disclosure relates to a power-off controlling circuit and a power-off controlling method.
Integrated circuits (IC) are configured to include many elements such as semiconductor devices. In recent years, thanks to advancements in fine processing technology of semiconductor devices, speeding up and high function of data processing have been realized. On the other hand, with the miniaturization of semiconductor devices, there has been a problem that leakage currents generated from semiconductor devices exponentially increase and thus power consumption of integrated circuits increase. Restraining leakage currents reduces power consumption of integrated circuits. Conventionally, generation of useless leakage currents can be restrained by turning off power in the integrated circuits when the integrated circuits are not operated.
However, the conventional method for restraining leakage currents, that is to say, a power-off method of integrated circuits is a method for turning off power regardless of the size of leakage currents occurred at the semiconductor devices when the integrated circuits are not operated. However, depending on the size of leakage currents, in this method, the power consumption of integrated circuits may increase adversely. In other words, the conventional power-off method of integrated circuits is effective when the amount of used electricity capable of being reduced by restraining leakage currents exceeds the amount of used electricity (electric power overhead) required for power-off operations and power-on operations because the leakage currents are large. On the contrary, this method has increased power consumption of integrated circuits when the amount of used electricity capable of being reduced by restraining leakage currents is smaller than the electric power overhead because the leakage currents are small.
In particular, since the size of leakage currents dynamically changes due to ambient surrounding and heat generation from integrated circuits owing to characteristics that the leak currents exponentially increase by the rise of temperature of a semiconductor device, for example, a transistor, it is desired that power-off is dynamically controlled according to the size of leakage currents. However, since the integrated circuit has a terminal for measurement and also a separate large-scale measurement circuit is required in order to directly measure leakage currents of a circuit during operations, there is a problem that the circuit is complicated and thus has an increased cost.